JPH0569733B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Field of Application] The present invention relates to a shift control device for an automatic transmission for a vehicle. [Prior Art] A vehicle travels by the frictional force generated between the drive wheels and the road surface. Therefore, if the driving force applied to the drive wheels is greater than the frictional force, the drive wheels will spin idly. Wheel spinning not only wastes the energy generated but also wears out the tires.
Therefore, it is desirable to prevent such idling of the drive wheels from occurring. Therefore, when designing a vehicle, engine output, gear ratio of the transmission, and tire speed have traditionally been adjusted to balance the driving force transmitted to the drive wheels and the frictional force generated between the road surfaces in each driving state. Characteristics etc. were set appropriately. However, the road surface assumed when designing a vehicle is
Friction coefficient μ is 0.6 to 0.7 like asphalt pavement.
Therefore, when driving a vehicle on a low-μ road with a low coefficient of friction μ, such as a snowy road, frozen road, or gravel road, the drive wheels tend to spin idly. In order to prevent the drive wheels from spinning even on such low-μ roads, conventional methods have been used to reduce the amount of drive provided to the drive wheels by suppressing engine output when a situation occurs where the drive wheels are spinning. A device to reduce the force has been considered (Japanese Patent Application Laid-open No. 58-38347). However, in such devices, the throttle valve, which is normally linked to the accelerator pedal and is opened and closed, is separated from the accelerator pedal so that the throttle valve can be opened and closed independently of the operator's operation of the accelerator pedal. However, there was a problem in that the equipment was complicated and expensive. [Object of the Invention] In view of such conventional problems, an object of the present invention is to solve the problem by changing the gear ratio of the transmission when the driving wheels are likely to spin. , suppresses the driving force transmitted to the drive wheels,
The purpose is to prevent the drive wheels from spinning regardless of the road surface condition. [Configuration of the invention] The configuration of the present invention for achieving this purpose is described as the first
This will be explained using figures. A vehicle speed sensor detects vehicle speed, and an engine load sensor detects a physical quantity representing engine load (hereinafter referred to as engine load).
The gear selection means stores in advance a gear shift pattern that determines the gear to be selected using the vehicle speed and engine load as parameters, and uses both the vehicle speed and engine load data detected by the vehicle speed sensor and the engine load sensor. Therefore, the gear position determined in the shift pattern is read out and set as the gear position to be selected. On the other hand, the wheel acceleration detecting means detects the acceleration of the driving wheels of the vehicle, and the predicted acceleration detecting means detects the acceleration of the driving wheels of the vehicle by the driving force applied from the engine to the driving wheels when the driving wheels are not idling. Find the expected acceleration of the vehicle. Then, the determining means compares the acceleration determined by the expected acceleration calculating means and the acceleration detected by the wheel acceleration detecting means, and determines whether the latter is larger than the former. When the determination means determines that the wheel acceleration is greater than the expected acceleration, the gear change means changes the gear read by the gear selection means to a high speed side by a predetermined number of gears. In the drive means, the gear change control actuator in the automatic transmission is driven so as to realize the gear changed by the gear changing means and ultimately to be selected. Therefore, the acceleration of the driving wheels detected by the wheel acceleration detection means is constantly monitored, and when the driving wheels do not idle, the driving means is operated to select the gear position determined by the gear selection means. When the drive wheels are idling, the gear changing means changes the gear determined by the gear selecting means to change the gear ratio so that the gear is on the high speed side. [Effects of the Invention] According to the present invention, when the drive wheels are not idling, the gear of the automatic transmission is set to the normally selected gear. When slipping occurs, the gear is set to the high speed side and the driving force transmitted to the drive wheels is suppressed.
It is possible to avoid a situation in which the drive wheels spin regardless of the road surface condition. Moreover, according to the present invention, only a small change is made to the control content in the shift control device of the automatic transmission, and no structural change is required, so that the effect can be realized extremely easily and at low cost. [Example] Hereinafter, an example of the present invention will be described with reference to the drawings. FIG. 2 is a schematic configuration diagram of one embodiment. In the figure, 11 is a vehicle speed sensor, 12 is a throttle sensor, 20 is a control circuit, and 31 to 33 are solenoids. The vehicle speed sensor 11 is a well-known sensor that is located in an automatic transmission (not shown) or a speedometer (not shown) and generates a pulse signal whose frequency is proportional to the vehicle speed.
2 consists of a potentiometer whose movable contacts are operated in accordance with the opening and closing operations of the throttle valve, and a constant voltage circuit 25 in the control circuit 20.
A constant voltage is supplied from the throttle valve to generate an analog voltage proportional to the throttle valve opening. The throttle sensor 12 constitutes an engine load sensor in the present invention. The control circuit 20 is mainly composed of a computer 21 which is a general-purpose microcomputer, and has an analog circuit for inputting signals to the computer 21.
It has a digital (A/D) converter 26, an input buffer 27, and an output buffer 28 for outputting a signal calculated by the computer 21.
The A/D converter 26 converts the voltage signal generated by the throttle sensor 12 into a digital signal according to instructions from the computer 21, and inputs the digital signal into the computer 21 as a throttle opening signal. Pulse signals generated by a known crank angle sensor 13 and vehicle speed sensor 11 provided in a distributor (not shown) are input to a computer 21.
When the pulse signals from the crank angle sensor 13 and the vehicle speed sensor 11 are input to the computer 21, they become interrupt request signals, and the pulse signals from the crank angle sensor 13 become interrupt request signals.
When the signal from the vehicle speed sensor 11 is interrupted, the engine speed is calculated, and when the signal from the vehicle speed sensor 11 is interrupted, the vehicle speed is calculated. The control circuit 20 also includes drive circuits 22 to 24 for converting the signal output from the output buffer 28 into drive signals for the solenoids 31 to 33, and supplies a constant voltage to each circuit in the control circuit 20. It has a constant voltage circuit 25. Constant voltage circuit 25
A power supply voltage is supplied to the drive circuits 22 to 24 by a battery 41. Note that only a part of the constant voltage and power supply voltage supply circuits are shown, and most of them are omitted. The drive circuits 22 to 24 all have the same configuration,
Only the drive circuit 22 is shown in detail. As is clear from this, the drive circuit 22 includes NPN type transistors 2 which are Schmitt connected to each other.
2a, 22b, and a PNP type transistor 2 connected to the transistor 22b by Darlington.
When a predetermined low-level voltage signal is output to the corresponding output terminal of the output buffer 28, the transistor 22a becomes non-conductive and the transistors 22b and 22c become conductive. The drive circuits 22 and 23 constitute part of the drive means in the present invention. The solenoids 31 to 33 are solenoids of solenoid valves (not shown) disposed in the automatic transmission, and when the solenoids 31 and 32 are energized or de-energized, the automatic transmission is activated as shown in Table 1. It is now possible to select the following gears. Therefore,
The solenoids 31 and 32 constitute actuators in the present invention.

[Table] In Table 1, OD means overdrive. Further, the solenoid 33 controls lock-up in the automatic transmission by being energized or de-energized. As is well known, the operation of the computer 21 is controlled by a program stored in a memory (not shown) within the computer 21. The contents of the program will be explained below with reference to flowcharts shown in FIGS. 3 to 7. FIG. 3 is a general flowchart of the main processing routine. When the main routine is started, first, in step 100, registers are initialized, and then, in step 200, a slip determination is performed. This is to determine whether or not the drive wheels are idling. Also,
In step 300, the gear position to be selected is determined from the vehicle speed and throttle opening (engine load), and in step 400, the gear position determined in step 300 is changed as appropriate based on the result of the determination in step 200. do. That is, when it is determined in step 200 that the drive wheels are idling, the gear position determined in step 300 is changed to a high speed side by a predetermined number of speeds. In step 500, a signal is output to the output buffer 28 to achieve the gear changed in step 400 and finally selected. FIG. 4 shows the acceleration calculation processing routine, 1
This is an interrupt routine that is activated every second. When this routine is started, first, the process of step 610 is performed, and a calculation for determining the vehicle speed V is performed.
This is the interval at which the routine is invoked.
It is obtained by counting the number of pulse signals output from the vehicle speed sensor 11 per second and multiplying the counted number by a constant. Data regarding the determined vehicle speed V is stored in a memory within the computer 21. In step 620, the vehicle speed V obtained in step 610 and the vehicle speed Vo obtained in the previous process are used.
Find the difference between the two and use the result as the wheel acceleration V.
It is still stored in memory. And step
At 630, the vehicle speed V determined at step 610 is
is stored in memory as Vo and used for the next step.
Used for processing 620. FIG. 5 is a flowchart showing details of step 200 in FIG.
In this step, the acceleration of the vehicle that is expected to be generated by the driving force applied from the engine to the drive wheels in a state where the drive wheels are not idling is determined. Also,
In steps 221 to 227, the predicted acceleration of the vehicle as described above is compared with the acceleration of the driving wheels determined in step 620 of FIG. 4, and it is determined whether the latter is greater than the former. First, in step 211, based on the map of vehicle speed V, engine speed Ne, and gear ratio T,
A torque ratio t, which is the ratio between the torque generated by the engine and the output shaft torque of the automatic transmission, is determined. Further, in step 212, the vehicle acceleration α is determined by the calculation formula K·θt·t−L. Here, θt is the throttle opening, and K and L are constants. In other words, step
In steps 211 and 212, a torque ratio t determined by the driving state of the vehicle at that time is determined, and an expected vehicle acceleration is determined based on the torque ratio t and the throttle opening θt. Next, in step 213, it is determined whether the determined vehicle acceleration α is greater than the road surface slip rate μ. In this case, μ is the slip rate on a paved road, 0.7. However, the slip rate of the road surface may be detected each time, and the detected value may be set as μ. In step 213, if the acceleration α is greater than the slip rate μ, the process proceeds to step 214, where α is replaced by μ. In other words, the processing in steps 213 and 214 does not make the acceleration α larger than the slip rate μ.
This is because acceleration exceeding the slip rate is impossible. After the vehicle acceleration α is determined in steps 213 and 214, the process proceeds to step 221, where:
In step 620 of FIG. 4, it is determined whether the wheel acceleration V. determined and stored in memory is greater than the vehicle acceleration α. If the wheel acceleration V. is larger than the vehicle acceleration α, it means that the drive wheels are idling, so in step 222 the slip counter SC is set to "1" and the process proceeds to step 223.
In step 223, the vehicle acceleration β, which is slightly larger than the vehicle acceleration α, is determined by the calculation formula M·α+N. Here, M and N are constants, for example, M is 1.2 and N is 0.2. In step 224,
It is determined whether the wheel acceleration V. is larger than the vehicle acceleration β. If the wheel acceleration V. is greater than the vehicle acceleration β, the process proceeds to step 225, where the slip counter SC is set to "3". Further, in step 226, the wheel acceleration V is set to a constant value C.
Determine whether it is smaller than . The constant value C is
If the wheel acceleration V is smaller than α and β and smaller than this constant value C, it is assumed that the drive wheels are not slipping, and a slip counter SC is set to 0 in step 229. Therefore, by performing steps 221 to 227, if the drive wheels are idling, the slip counter SC is set to "1", and if the idling is severe, the slip counter SC is set to "1". The slip counter SC is set to "3" and if no slipping occurs, the slip counter SC is set to "0". FIG. 6 is a flowchart showing details of step 300 in FIG. 3, and here, the vehicle speed and throttle opening (engine load) at that time are
Accordingly, the gear positions of the gear change pattern determined as shown in FIG. 8 are read out, and the gear position to be selected is determined. The speed change pattern shown in FIG. 8 is stored in the memory of the computer 21, and the speed change pattern shown in FIG.
It is determined using the output shaft rotation speed and throttle opening of the automatic transmission as parameters. Here, the solid line is an upshift pattern for switching from a low speed side to a high speed side, and the broken line is a shift down pattern for switching from a high speed side to a low speed side. Also, OD stands for overdrive. Similar to this shift pattern, a lock-up pattern is also determined (not shown). In FIG. 6, in step 311, "4" is set in register N, and the desired gear stage is set to 4th speed. Next, in step 312, the shift memory
It is determined whether the gear stage actually selected and stored in the SHM matches "4" set in the register N. If the actual gear position is 4th speed and the value in the shift memory SHM and the value in the register N match, an affirmative determination is made in step 312 and the process proceeds to step 324. From the throttle opening θt and the value of register N, the OD in the shift pattern in Fig. 8 is determined.
3 Read the shift point Vt of the downshift pattern.
Then, in step 325, the read shift point is
Compare Vt with the vehicle speed SPD stored in the memory, and if the vehicle speed SPD is greater than the shift point Vt, there is no need to downshift, so an affirmative decision is made in step 325 and the processing of this routine ends. . Therefore, the value of register N remains "4". However, when the vehicle speed SPD is smaller than the shift point Vt, it is necessary to downshift, so a negative determination is made in step 325, and the process proceeds to step 326, where the value of register N is set to "4".
to "3". On the other hand, when processing step 312, if the actual gear position is 3rd speed and the value in the shift memory SHM is "3", a negative determination is made in step 312, and the process proceeds to step 313, where the throttle Opening degree θt
The shift point Vt of the 3→OD shift up pattern in the shift pattern shown in FIG. 8 is read out from the value of the register N and the value of the register N. Then, in step 314, the read shift point Vt and the vehicle speed SPD are compared, and if the vehicle speed SPD is greater than the shift point Vt, it is necessary to shift up, so this step 314 is determined to be affirmative and the main routine is started. The process ends. Therefore, the value of register N remains "4". However, when the vehicle speed SPD is smaller than the shift point Vt, there is no need to shift up, so a negative determination is made in step 314 and the process proceeds to step 315, where the value of register N is changed from "4" to "3". Ru. Next, in step 316, shift memory SHM
It is determined whether or not the value of register N matches the value of register N, and if they are both "3", an affirmative decision is made in step 316, and step 316 is executed.
Proceed to 327. In step 327, the shift point Vt of the 3→2 downshift pattern is read out in the same manner as in step 324, and in step 328, the shift point Vt is compared with the vehicle speed SPD. After that, steps 328 and 329
The processing in steps 325 and 326 is the same as that in steps 325 and 326, except that the value of register N is different, and the processing in steps 330, 331, and
332 is similar to these. Also, step 317,
The processing of steps 318, 319 and 321, 322, 323 is similar to that of steps 313, 314, 315, respectively. In this way, the gear stage to be selected is stored in register N. Note that the gear position when register N is set to "4" is overdrive. FIG. 7 shows details of step 400 in FIG. 3. In step 411, the value of the slip counter SC is added to the value of the register N, and the value of the register N is set again. The value of the register N represents the gear stage to be selected determined from the vehicle speed and throttle opening, and the value of the slip counter SC corresponds to the slip state of the drive wheels. Since the value is set to "1" or more, by performing the process of step 411, the gear stage to be selected is changed to the high speed side in accordance with the idle state of the drive wheels. Next, in step 412, it is determined whether the value of register N is greater than "4", and if it is greater than "4", in step 417, the value of register N is set to "4". In other words, the highest speed gear is overdrive, so register N
When the value becomes larger than "4" corresponding to overdrive, it is set to "4". By sequentially executing the programs explained in the flowcharts of FIGS. 3 to 7 above,
The gear position determined by the vehicle speed and throttle opening is changed depending on whether or not the drive wheels are spinning, and the gear position that should be finally selected is shown in Figure 2. In the computer 21
The output buffer 28 outputs the signal to be selected, and controls the energization and de-energization of the solenoids 31 and 32. For example, when the gear stage to be selected is 3rd speed, the output buffer 28 is connected to the drive circuit 2.
A high level electric signal is output to the drive circuit 2, and a low level electric signal is output to the drive circuit 23. Therefore, the solenoid 31 is de-energized, and the solenoid 32 is
Power is applied. As a result, as is clear from Table 1 above, the automatic transmission is set to 3rd gear. The output buffer 28 also outputs a voltage signal to the drive circuit 24 depending on whether or not lock-up occurs, and therefore, the drive circuit 24 controls energization and de-energization of the solenoid 33 to determine whether or not lock-up occurs. It will be controlled. In the flowcharts of FIGS. 3 to 7, steps 300 and 311 to 332 correspond to the gear selection means of the present invention, and steps 610 to 332 correspond to the gear selection means of the present invention.
The process in step 630 corresponds to the wheel acceleration detection means in the present invention, and the process in steps 211 to 214 corresponds to the expected acceleration calculation means in the present invention.
The processing in steps 221 to 227 corresponds to the determining means in the present invention, the processing in steps 411 to 413 corresponds to the gear change means in the present invention, and the processing in step 500 corresponds to the driving means in the present invention.

[Brief explanation of the drawing]

FIG. 1 is a claim correspondence diagram, FIG. 2 is a schematic configuration diagram of an embodiment of the present invention, FIGS. 3 to 7 are flowcharts showing the program of the computer in FIG. 2, and FIG. , is a diagram showing an example of a shift pattern. DESCRIPTION OF SYMBOLS 11... Vehicle speed sensor, 12... Throttle sensor, 13... Crank angle sensor, 20... Control circuit, 21... Computer, 22-24... Drive circuit, 31-33... Solenoid (actuator).

Claims (1)

[Scope of Claims] 1. A vehicle speed sensor that detects vehicle speed; an engine load sensor that detects a physical quantity representing engine load (hereinafter referred to as engine load); and a gear shift that should be selected using vehicle speed and engine load as parameters. A gear shift pattern with predetermined gears is stored in advance, and the gear gear determined in the gear shift pattern is read out based on both vehicle speed and engine load data detected by a vehicle speed sensor and an engine load sensor, and is set as the gear gear to be selected. gear selection means; wheel acceleration detection means for detecting the acceleration of the drive wheels of the vehicle; Expected acceleration calculating means for calculating acceleration; and determining means for comparing the acceleration calculated by the expected acceleration calculating means with the acceleration detected by the wheel acceleration detecting means and determining whether the latter is greater than the former. and, when the determination means determines that the wheel acceleration is larger than the expected acceleration, a gear change means changes the gear read by the gear selection means to a high speed side by a predetermined number of gears. and a driving means for driving a shift control actuator in the automatic transmission so as to realize the gear changed by the gear changing means and finally selected. Shift control device for automatic transmission for vehicles.